In general, a display device refers to monitors for a TV or a computer as a whole, and includes a display element forming an image and a case supporting the display element.
Examples of the display element may include a plasma display panel (PDP), a liquid crystal display (LCD), an electrophoretic display, and a cathode-ray tube (CRT). The display element may include an RGB pixel pattern and an additional optical filter for implementing an image.
The optical filter may include at least one of a reflection prevention film preventing the external light that is incident from the outside from being reflected to the outside again, a near IR shielding film shielding the near IR generated in the display element in order to prevent a mis-operation of electronic devices such as remote controllers, a color correction film increasing the color purity by controlling a color tone by including a color control dye, and an electromagnetic wave shielding film that shields the electromagnetic wave generated in a display element when a display apparatus is driven. Here, the electromagnetic wave shielding film includes a transparent substrate and a metal mesh pattern provided on the substrate.
Meanwhile, with regard to the display apparatus, as the distribution of IPTVs is accelerated, a demand for a touch function that uses hands as a direct input apparatus without a separate input apparatus such as remote controllers is growing. Further, a multi-touch function that is capable of recognizing a specific point and writing is also required.
The touch sensor performing the aforementioned function may be classified into the following types according to a signal detection manner.
That is, the touch sensor includes a resistive type, in which a position pressed by pressure in a state where a direct-current voltage is applied is sensed based on a change in a current or voltage value, a capacitive type using capacitance coupling in a state where an alternating-current voltage is applied, an electromagnetic type, in which a selected position is sensed based on a change in a voltage in a state where a magnetic field is applied, and the like.
Among them, the resistive type and capacitive type touch sensors that are most extensively spread recognize a touch by a change in an electric contact or capacitance by using a transparent conductive film, such as an ITO film. However, since the transparent conductive film has high resistance of 100 ohm/square or more, sensitivity is degraded when the transparent conductive film is manufactured in a large scale, and as the size of screen is increased, the cost of the ITO film is rapidly increased, so that it is not easy to commercialize the touch sensor. In order to overcome the problem, there is an effort to implement a transparent conductive film by using a metal pattern having high conductivity.